Segmented contact assembly having pivotal and sidewise-rotatable contact segments



July 13, 1965 SEGMENTED CON T ASSEMB SIDEWISE-ROTATABLE Filed Dec.

. E. GAUTHIER LY HAVING PIVOTAL AND CONTACT SEGMENTS 12, 1965 FIG.\

v lo GEORGE 3223 A TTOIPNE Y United States Patent 3,14,934 SEGMENTEDCONTACT ASSEMBLY HAVHIG FEV- OTAL AND SIDEWiSE-RUTATABLE CONTACTSEGMENTS George E. Gauthier, Plainville, Conn., assignor to GeneralElectric Company, a corporation of New York Filed Dec. 12, 1963, Ser.No. 330,126 3 Claims. (Cl. 200-466) My invention relates to multipleelectrical contact assemblies, and more particularly to multiple contactassemblies of the type comprising a plurality of relatively heavycontact members pivotally supported on a common pivot pin and movable asan assembly between open and closed circuit positions with respect to acorresponding plurality of stationary contacts.

Devices utilizing contact assemblies of the type described areordinarily designed to carry substantial amounts of current, such forexample as 1000 or more amperes. With such high currents, even arelatively small amount of resistance at contact interfaces in theclosed circuit position can give rise to excessive amounts of heat,causing deterioration of adjacent metal parts and supporting structure.In order to maintain good conductivity with low temperature rise, it isessential that the surfaces of meeting contacts shall each seat inconforming flatwise engagement with each other. In accordance with theprior art, it has been common practice to pivotally support each of thecontact members of an assembly of contacts. For economy of manufactureand compactness, it is desirable to support all contact members of agiven assembly on a common pivot pin. While each of the contact membersis individually movable in its plane of rotation, that is, at rightangles to the axis of the pivot pin, the contact members are notindividual 1y movable in any other plane, since they are all carried bythe same pivot pin. It has been found that the stationary contactsurfaces, with which the movable contacts must meet, often do not alllie in perfectly parallel planes. Therefore, in the closed circuitposition, not all of the movable contacts can seat themselves inconformity with the flat surfaces of the corresponding stationarycontacts. This increases the resistance at the contact interface andcontributes to heating of the contact assembly.

It is an object of the present invention to provide a multiple contactassembly comprising a plurality of contacts supported on a common pivotpin in which each of the contacts is individually capable of seatingitself in flatwise conformity with its corresponding stationary contacteven though such stationary contacts do not all lie in the same orparallel planes.

It is another object of the invention to provide such a contact assemblywhich is no more complicated or expensive than prior art contactassemblies.

In accordance with the invention in one form, a movable contact assemblyis provided comprising a generally channel-shaped contact arm having apivot pin passing between the opposed side wall portions thereofadjacent one end. A plurality of contact members, comprisingsubstantially rectangular blocks of conductive material, are pivotallysupported in side-by-side relation on the pivot pin, and each biased forrotation about the pivot pin by a compression spring between a portionof the contact and a corresponding portion of the contact arm. Rotationof each contact member about the pivot pin is limited by engagement ofan extension of the contact with a corresponding portion of the contactarm.

In addition to rotational adjustment, sidewise adjusting movement ofeach of the contact members is provided for by shaping the hole throughwhich the pivot pin passes in each of the contact members in such a waythat the 3,194,934 Patented July 13, 1965 outer portions of the hole'are of greater diameter than the central portion. Contact between thepivot pin and each of the contact members takes place substantiallyexclusively at the reduced diameter center portion. Each of the contactmembers is therefore permitted to rock axially or to wobble on the pivotpin, as well as to rotate thereabout, thereby assuring complete freedomto seek conformity with the corresponding surface of the stationarycontact member.

The invention will be more fully understood from the following detaileddescription, and its scope will be pointed out in the appended claims.

In the drawings,

FIGURE 1 is a side elevation view of a portion of an electric switch orcircuit breaker incorporating the invention, and

FIGURE 2 is a sectional view of the contact arm of the switch of FIGURE1 taken substantially as indicated on the line 2--2 of FIGURE 1, butwith the movable contact assembly in the closed circuit position.

Referring to FIGURE 1, the invention is shown as incorporated in anelectric switching device comprising an insulating base It) on which ametallic supporting frame 11 is mounted by suitable means such as byscrews 12 and 13. The frame member 11 comprises two spaced apartparallel side plate portions, only one of which is shown in FIGURE 1,the side nearest the observer being omitted to show the working parts.

A generally channel-shaped movable contact arm 14 is pivotally supportedon a pivot pin 15 extending between the side plates of the frame 11. Thecontact arm 15 is adapted to be ganged to other similar contact arms,not shown, by a contact cross-arm 16. The contact arm 14 carries anassembly of three movable contact members 17, 18, w, all pivotallysupported on a common pivot pin 20 extending between the sides of thechannel-shaped contact arm 14. The pivot pin 2t) is retained in place onthe channel-shaped contact arm 14 by means of a snap-on type washer 20Awhich fits in a groove in the pin 20 (see FIGURE 2). Each of the contactmembers 17, 18, 19 is biased for rotation about the pivot pin 20 by acorresponding compression spring 21 (only two shown). The upper portionof each of the springs 21 is retained in an inverted cupshaped retainer24 carried by the contact arm 14. Rotation of each of the contactmembers 17, 18, 19, about the pivot pin 20 is limited by engagement ofan opposite end portion thereof with the bight portion of the contactarm 14.

The movable contacts 17, 18, 19 are electrically connected by means offlexible conductive braids 25, with a terminal 26 anchored to the base10 by the same screw 13 which retains the frame 11 in place.

The contacts 17, 18 and 19 are adapted to engage correspondinglypositioned relatively stationary contacts 27, 28, 29, all fixedlymounted on a stationary terminal strap 30 supported on the base 10.

The contact arm 14 is movable between open and closed circuit positionsso as to move the movable contacts 17, 18, 19 into and out of engagementwith the stationary contacts 27, 28, 29, by suitable operating means,not shown, engaging the contact arm at pivot pin 31.

Referring to FIGURE 2, in accordance with the invention the contacts 17,18, and 19 are each enabled to seat themselves in conformity with theflat surfaces of the stationary contacts 27, 28, 29, by providing eachof the contacts 17, 18 and 19 with specially shaped holes through whichthe pivot pin 20 extends. As shown in FIGURE 2, each of the holes 33includes a pair of enlarged outer portions 33A, leaving a reduceddiameter inner portion defining a centrally positioned raised abutmentor rib 35, 36, 37 in each of the contacts 17, 18 and 19.

As shown in FIGURE 2, in the event that the stationary contacts 27, 28,29 are mounted on the line terminal 30 in such a way that their upperflat surfaces are not exactly parallel to each other, the movablecontacts will nevertheless be able to seat themselves in conformitythereto by reason of the ability of each of the movable contact membersto rock side-wise on the pivot pin 2% because of the particular mountingprovisions described. This assures good electrical and thermal contact,andsubstantially reduces heating at the contact interfaces.

.While the invention has been described in only one particularembodiment, it will be readily apparent that modifications thereof mayreadily be made by those skilled in the art, and it is thereforeintended by the appended claims to cover all such modifications as fallwithin the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters 7 Patent of theUnited. States is:

1. An electric contact assembly comprising:

(a) a movable contact arm;

- (b) a pivot pin carried by said contact arm;

(c) 'a plurality of individual contact members supported on said pivotpin;

(d) each of said contact members having a hole therethroughthrough whichsaid pivot pin extends, said holehaving a transverse dimension at eachend thereof substantially greater than the diameter of said pivot pin ata point adjacent said ends of said hole, said hole having a transversedimension at the central portion thereof substantially equal to thediameter of said pivot pin at a point adjacent said central portion ofsaid hole, whereby each of said contact members is rotatable aboutsaidpivot pin in a plane perpendicular to the axis of said pivot pin andeach of said contact members is rotatable a limited amount in a planeparallel to said axis of said pivot pin.

2. A movable contact assembly comprising:

(a) a contact arm;

(b) a pivot pin carried by said contact arm;

(0) a plurality of individual contact members supported on said pivotpin;

(d) each of said contact members having a hole therethrough for saidpivot pin, said hole having enlarged portions at each end thereof and areduced diameter central portion, and each of said contact memberscontacting said pivot pin substantially entirely at said reduceddiameter central portion;

(e) whereby each of said contact members is rotatable in a planeperpendicular to the axis of said pivot pin and also rotatable in atleast one plane parallel to said axis of said pivot pin.

3. An electric switching device comprising:

(a) an insulating support;

('0) a plurality of spaced stationary contacts mounted on said support;

(0) a contact arm pivotally mounted on said support;

(d) a plurality of movable contact members carried by said contact armand each adapted to engage one of said stationary contacts respectively;

(e) a pivot pin of predetermined diameter carried by said contact arm;

. (f) each of said contact members having a dimension in the directionof said pivot pin at least twice said predetermined diameter;

(g) each of said contact members having a hole therethrough receivingsaid pivot pin, each of said holes comprising an enlarged portion ateach end thereof and a reduced diameter central portion, each of saidcontact members being supported on said pivot pin substantially entirelyby contact with reduced diameter central portion; a

(h) said stationary contacts each having a substantially planar uppersurface, said planar upper surfaces of said stationary contacts lying inplanes other than parallel planes;

(i) said relatively movable contacts each being rotatable about saidpivot pin in a plane perpendicular to said axis of said pivot pin andalso being pivotal about said pivot pin in at least one plane parallelto said axis of said pivot pin;

(j) whereby each of said relatively movable contact members may seatitself in fiatwise conformity with its corresponding stationary contactto provide optimum electrical and thermal engagement therewith.

Ret'erenees Cited by the Examiner UNITED STATES PATENTS 1,328,450 1/20Reisbach 200166 2,082,794 6/37 Ebert et al. 200165 X 2,094,473 9/37Schmitt 200114 X 2,794,086 5/57 Barrett 200-67 BERNARD A. GILHEANY,Primary Examiner.

2. A MOVABLE CONTACT ASSEMBLY COMPRISING: (A) A CONTACT ARM; (B) A PIVOTPIN CARRIED BY SAID CONTACT ARM; (C) A PLURALITY OF INDIVIDUAL CONTACTMEMBERS SUPPORTED ON SAID PIVOT PIN; (D) EACH OF SAID CONTACT MEMBERSHAVING A HOLE THERETHROUGH FOR SAID PIVOT PIN, SAID HOLE HAVING ENLARGEDPORTIONS AT EACH END THEREOF AND A REDUCED DIAMETER CENTRAL PORTION, ANDEACH OF SAID CONTACT MEMBERS